The present invention relates to a power conversion system in liaison with a power generating apparatus to cooperate with a commercial AC power source.
Recently, use of distributed power sources has been studied as a power source for housing. A fuel cell directly converts chemical energy to electric energy, which causes high conversion efficiency. A method of restraining power to be supplied to the housing and reducing electric charges has been studied by charging and discharging power generated by the fuel cell to and from a secondary battery.
JP-A-2002-63927 describes an example of a system for supplying power from a secondary battery to the housing when power failure has occurred during a time from starting the fuel cell to starting its power generation.
As disclosed in JP-A-2002-63927, however, a method of connecting the commercial AC power source with the secondary battery through a cooperative inverter and an AC/DC converter, needs to maintain the voltage of secondary battery at a high voltage enough for system cooperation. Thus, this method cannot be restrained a possible power loss occurring in an auxiliary-devised power source supplying circuit when the fuel cell generates no power.